1. What is the difference between VPN and MPLS?2. What is MPLS and why it is being so popular in short time?3. What is the protocol used by MPLS?4. MPLS works on which layer?5. What is the difference between P and PE router?6. Can I make my PE router as P?7. Two routers are having 4 equal cost links, how many ldp sessions will be established? 8. My LDP router id, OSPF router id and BGP router id is different, will it work to forward the traffic of customers or not?9. What is Penultimate Hop Popping and why it is required? Which router performs the PHP function?10. I am receiving aggregate label, what does it mean? 11. What are the different types of labels?12. How to make customer route unique?13. What is the difference between RD and RT?14. Can I assign a same RD to two different customers?15. Is RD travels in route update?16. My customer is having three branches and all are attached to three different PEs, In this case can I use the different vrf names?17. What is downstream on demand?18. How to filter MPLS labels?19. What is the default range of MPLS labels in Cisco routers ? How to extend that range?20. Without route reflector can I implement MPLS?21. What is the difference between VPNv4 and IPv4 address family?22. What is MP-iBGP? Can we use normal BGP in lieu of MP- iBGP?23. What is LIB, LFIB?24. What is CEF and without enabling CEF, can we make MPLS work?25. I am receiving end to end customer routes on various PE but not able to ping those routes, what’s could be the problem?26. What is explicit null and implicit null?27. Default timers of LDP?28. Does LDP require OSPF, IS-IS or BGP?29. In neighbor discovery command, I am receiving only xmit, what does it mean?30. What is transport address? 31. What is the RFC of MPLS?32. Why MPLS is called multi protocol?33. What is the difference between MPLS, SSL and IPSec?34. I am using different vendor products and want to implement TDP, what type of challenges will you face?35. Does MPLS support IPv6?36. Can I use the existing IPv4 MPLS backbone for IPv6?37. Define various troubleshooting commands in MPLS?38. What is forward equivalence class aka FEC?39. What is adjacency table?40. Difference between MPLS IP and MPLS Label Protocol LDP command?41. If MPLS get disable, will it harm my IGP or IPv4 traffic?